Due to HW design errors in rev2, some signals must be reconfigured
to avoid malfunction or possible electrical damage.
- Setup UART3 RTS/CTS lines as GPIOs as polarity has been swapped on rev2
- Make sure to set GPIO1_IO12 (USB1_OTG_PWR) in input mode and remove usb0
  port from u-boot device tree to avoid conflicting drivers when external
  host is attached.

Signed-off-by: Thomas Schaefer <thomas.schaefer@kontron.com>